Electric field assisted ranque-hilsch (efarh) vortex tube for enhanced product separation and transformation

ABSTRACT

An improved apparatus for the separation of gas or gas-vapor, as well as simultaneous product transformation or conversion of one or more of the separated gas or gas-vapor species, includes modification of a Ranque-Hilsch vortex tube to include an electric field internal to the vortex tube, created either by an applied potential or induced by temperature-dependent triboelectric effects, or a combination of both. The electric field is used to enhance separation of gaseous components, with particular emphasis on separation of CO 2  from a gaseous mixture, and to promote subsequent conversion of the resulting separated gaseous product or products.

CROSS REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE STATEMENT

This application claims priority to U.S. Ser. No. 63/243,480 filed Sep. 13, 2021, the entire content of which is hereby expressly incorporated herein by reference.

BACKGROUND 1. Field of the Disclosure

The present disclosure relates to vortex tubes, and more specifically to Ranque-Hilsch vortex tubes modified to support an internal electric field that enhances separation of gaseous components.

2. Brief Description of Related Art

The rapid increase in the level of atmospheric carbon dioxide, CO₂, is a matter of great concern with respect to unwanted heating of the planet and resulting environmental consequences. To date, CO₂ separation and capture technologies are based upon the use of chemical adsorbents or cooling of the gas below the gas-liquid transition temperature. Both techniques are energy intensive, while chemical adsorbents have limited lifetimes.

A Ranque-Hilsch vortex tube [1,2] is a device with no moving parts capable of dividing high-pressure gaseous input flow, created by tangential injection of a compressed gas using one or more nozzles, into two low-pressure flows of different temperatures. As such, when compressed gas is injected into the tube, a strong vortex-like flow field is established, giving rise to a non-uniform temperature, or density, distribution within the tube. In counter-flow vortex tubes, the most common vortex tube design and superior in its separation properties, a fraction of the feed gas exits as a cold, or denser, stream through an opening in the central zone at one end near the tangential inlet, while the balance of the feed gas exits at the opposite end of the vortex tube as a hot, or less dense, peripheral stream through a throttle valve. While absolute numbers are dependent upon experimental variables, output hot exit temperatures of 200° C. and cold exit temperatures of −50° C. are not uncommon.

In the prior art, vortex tubes have been shown to provide partially separate gas mixtures. In 1964, Linderstrom-Lang reported use [3] of a counter-flow Ranque-Hilsch vortex tube for separating different gas mixtures, O₂—N₂, O₂—CO₂, and O₂—He, with a reported small amount of gas separation, well less than 1%. Linderstrom-Lang found superior gas separation with vortex tubes of short length where temperature separation is minimal, and superior temperature separation with vortex tubes of longer length where gas separation effects disappeared. In 2002, Kulkarni and Sardesai [4] reported the separation of a methane-nitrogen mixture using a vortex tube, achieving 1% or less separation efficiency, varying the inlet pressure as well as the hot exit pressure. In 2018, Yun and co-workers [5] reported the separation of CO₂ from an air-CO₂ mixture. For a CO₂-air gaseous input to the vortex, 11.1% CO₂ and 89.9% air, a maximum of 8.5% CO₂ separation was achieved between the gas streams exiting the cold and hot exits. In addition, as the input pressure varied maximum CO₂ separation was achieved at an experimentally determined mass fraction of the total input leaving the cold temperature exit.

Mohammadi and Farhadi [6] reported the use of a vortex tube for separation of liquefied petroleum gas, LPG, (mole fraction %: methane 2.91%, ethane 5%, propane 40.20%, propylene 7%, C₄₊ 44.80%) from a nitrogen (80.2%) and oxygen (19.8%) mixture. The significant difference in molecular weight between the different components enables a relatively high degree of separation efficiency. Operating at 2.36 bar, for an input of LPG (mole fraction 22%) and the N₂+O₂ mixture, they reported a maximum 87% separation efficiency as dependent upon the mole fraction of the gas leaving the cold exit. Similarly, with LPG as the input, in separating the C₄₊ components from the hydrocarbons of lighter molecular weight, a maximum separation efficiency of 78% was reported. Using computational models, Mohammadi and Garhadi suggest cascades of vortex tubes can be used to further purify the gas streams, as taught by Fekete [7], at efficiencies significantly greater than distillation columns.

SUMMARY OF THE DISCLOSURE

The present disclosure relates generally to a modified Ranque-Hilsch vortex tube having a cold end, a hot end, and a tube portion having a tube axis. The modified vortex tube is made of conductive metal. A cone valve is positioned in the hot end and spaced a distance from the tube. An electrically conductive wire is positioned and oriented along the tube axis, and the electrically conductive wire is electrically isolated from the tube portion.

In another embodiment, the modified Ranque-Hilsch vortex tube is used for separating and concentrating CO₂ from a gaseous input.

In yet another embodiment, a series of modified Ranque-Hilsch vortex tubes is used for separating and concentrating CO₂ from a gaseous input. A tube exit possessing the highest concentration of CO₂ can be used as an input for a subsequent modified vortex tube for further separation and concentration. The CO₂ separation efficiency increases with CO₂ concentration in the input gaseous stream, and the final output may be fed, partially or in whole, into a device that converts CO₂ into another chemical compound.

BRIEF DESCRIPTION OF THE DRAWINGS

Like reference numerals in the figures represent and refer to the same or similar element or function. Implementations of the disclosure may be better understood when consideration is given to the following detailed description thereof. Such description makes reference to the annexed pictorial illustrations, schematics, graphs, and drawings. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated, to scale or in schematic in the interest of clarity and conciseness.

In the drawings:

FIG. 1 illustrates the geometry of a counterflow Ranque-Hilsch vortex tube (RHVT).

FIG. 2 is a graphical representation of variation in CO₂ separation efficiency in accordance with the present disclosure.

FIG. 3 illustrates a block diagram of an exemplary series cascade of vortex tubes in accordance with the present disclosure.

FIG. 4 illustrates the geometry of a counterflow Electric Field Assisted Ranque-Hilsch (EFARH) vortex tube modified to support an internal electric field by introduction of a thin, electrically conductive wire oriented along the axis of the vortex tube. The axial wire and outer wall of the vortex tube are not in direct electrical contact.

FIG. 5 is an end-on illustration of the electric and magnetic field geometry generated within an Electric Field Assisted Ranque-Hilsch (EFARH) vortex tube.

DETAILED DESCRIPTION

Before explaining at least one embodiment in detail by way of exemplary language and results, it is to be understood that the present disclosure is not limited in its application to the details of construction and the arrangement of the components set forth in the following description. The present disclosure is capable of other embodiments or of being practiced or carried out in various ways. As such, the language used herein is intended to be given the broadest possible scope and meaning; and the embodiments are meant to be exemplary and not exhaustive. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.

Unless otherwise defined herein, scientific and technical terms used in connection with the present disclosure shall have the meanings that are commonly understood by those of ordinary skill in the art. Further, unless otherwise required by context, singular terms shall include pluralities and plural terms shall include the singular. The foregoing techniques and procedures are generally performed according to conventional methods well known in the art and as described in various general and more specific references that are cited and discussed throughout the present specification.

All patents, published patent applications, and non-patent publications mentioned in the specification are indicative of the level of skill of those skilled in the art to which this present disclosure pertains. All patents, published patent applications, and non-patent publications referenced in any portion of this application are herein expressly incorporated by reference in their entirety to the same extent as if each individual patent or publication was specifically and individually indicated to be incorporated by reference.

All of the compositions, assemblies, systems, and/or methods disclosed herein can be made and executed without undue experimentation in light of the present disclosure. While the compositions, assemblies, systems, and methods of the present disclosure have been described in terms of particular embodiments, it will be apparent to those of skill in the art that variations may be applied to the compositions and/or methods and in the steps or in the sequence of steps of the methods described herein without departing from the concept, spirit, and scope of the present disclosure. All such similar substitutions and modifications apparent to those skilled in the art are deemed to be within the spirit, scope, and concept of the present disclosure.

As utilized in accordance with the present disclosure, the following terms, unless otherwise indicated, shall be understood to have the following meanings:

The use of the term “a” or “an” when used in conjunction with the term “comprising” in the claims and/or the specification may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.” As such, the terms “a,” “an,” and “the” include plural referents unless the context clearly indicates otherwise. Thus, for example, reference to “a compound” may refer to one or more compounds, two or more compounds, three or more compounds, four or more compounds, or greater numbers of compounds. The term “plurality” refers to “two or more.”

The use of the term “at least one” will be understood to include one as well as any quantity more than one, including but not limited to, 2, 3, 4, 5, 10, 15, 20, 30, 40, 50, 100, etc. The term “at least one” may extend up to 100 or 1000 or more, depending on the term to which it is attached; in addition, the quantities of 100/1000 are not to be considered limiting, as higher limits may also produce satisfactory results. In addition, the use of the term “at least one of X, Y, and Z” will be understood to include X alone, Y alone, and Z alone, as well as any combination of X, Y, and Z. The use of ordinal number terminology (i.e., “first,” “second,” “third,” “fourth,” etc.) is solely for the purpose of differentiating between two or more items and is not meant to imply any sequence or order or importance to one item over another or any order of addition, for example.

The use of the term “or” in the claims is used to mean an inclusive “and/or” unless explicitly indicated to refer to alternatives only or unless the alternatives are mutually exclusive. For example, a condition “A or B” is satisfied by any of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

As used herein, any reference to “one embodiment,” “an embodiment,” “some embodiments,” “one example,” “for example,” or “an example” means that a particular element, feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearance of the phrase “in some embodiments” or “one example” in various places in the specification is not necessarily all referring to the same embodiment, for example. Further, all references to one or more embodiments or examples are to be construed as non-limiting to the claims.

Throughout this application, the term “about” is used to indicate that a value includes the inherent variation of error for a composition/apparatus/device, the method being employed to determine the value, or the variation that exists among the study subjects. For example, but not by way of limitation, when the term “about” is utilized, the designated value may vary by plus or minus twenty percent, or fifteen percent, or twelve percent, or eleven percent, or ten percent, or nine percent, or eight percent, or seven percent, or six percent, or five percent, or four percent, or three percent, or two percent, or one percent from the specified value, as such variations are appropriate to perform the disclosed methods and as understood by persons having ordinary skill in the art.

As used in this specification and claim(s), the words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”), or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

The term “or combinations thereof” as used herein refers to all permutations and combinations of the listed items preceding the term. For example, “A, B, C, or combinations thereof” is intended to include at least one of: A, B, C, AB, AC, BC, or ABC, and if order is important in a particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB. Continuing with this example, expressly included are combinations that contain repeats of one or more item or term, such as BB, AAA, AAB, BBC, AAABCCCC, CBBAAA, CABABB, and so forth. The skilled artisan will understand that typically there is no limit on the number of items or terms in any combination, unless otherwise apparent from the context.

As used herein, the term “substantially” means that the subsequently described event or circumstance completely occurs or that the subsequently described event or circumstance occurs to a great extent or degree. For example, when associated with a particular event or circumstance, the term “substantially” means that the subsequently described event or circumstance occurs at least 80% of the time, or at least 85% of the time, or at least 90% of the time, or at least 95% of the time. For example, the term “substantially adjacent” may mean that two items are 100% adjacent to one another, or that the two items are within close proximity to one another but not 100% adjacent to one another, or that a portion of one of the two items is not 100% adjacent to the other item but is within close proximity to the other item.

As used herein, the phrases “associated with” and “coupled to” include both direct association/binding of two moieties to one another as well as indirect association/binding of two moieties to one another. Non-limiting examples of associations/couplings include covalent binding of one moiety to another moiety either by a direct bond or through a spacer group, non-covalent binding of one moiety to another moiety either directly or by means of specific binding pair members bound to the moieties, incorporation of one moiety into another moiety such as by dissolving one moiety in another moiety or by synthesis, and coating one moiety on another moiety, for example.

As used herein, the term “gas” is used in its broadest sense and includes, for instance, gas mixtures, air, natural gas, a hydrocarbon mixture, gas-vapor mixtures, and/or the like.

The Ranque-Hilsch vortex tube, as it is commonly known, is a device with no moving mechanical parts, which converts a gas flow initially homogeneous in temperature into two separate flows of higher and lower temperatures. This separation of the one temperature-homogenous flow, which can be gaseous or liquid, into streams of higher and lower temperature is referred to as the temperature, or energy, separation effect. As seen in FIG. 1 , a vortex tube is comprised of one or more inlet nozzles, a vortex chamber, a cold-end orifice, and a hot end control valve. Due to the high input/operating pressures commonly used, vortex tubes may be constructed of a conductive material (e.g., conductive plastic), or more commonly made out of metals such as brass, aluminum, or stainless steel. The inlet nozzles have an axis that may be positioned tangent to a curve of an inner surface of the vortex tube so as to cause a vortex to form within the vortex chamber when compressed gas is passed through the inlet nozzles. The compressed gas can be within a range of 60 psi to 600 psi or about 4 bar to about 40 bar, for example. The hot end control valve may be a cone shaped valve positioned within the hot end orifice. In some embodiments, the cold-end orifice and/or the hot end orifice can each be fluidly connected to at least one of a storage tank and an inlet nozzle of another vortex tube.

Turning again to the drawings and in particular to FIG. 1 , certain non-limiting embodiments thereof relate to systems and methods for collection, separation and/or concentration of gas mixtures input to an exemplary vortex tube 10. In some embodiments, such systems and methods may additionally include subsequent storage and/or conversion of one or more of the separated gas species with components (e.g., integral components) to the vortex tube 10. In some embodiments, methods may include enhanced separation of gaseous components (e.g., separation of CO₂ from a gaseous mixture), and/or subsequent conversion of separated product with components integral to the vortex tube 10, for example. Further methods herein may include, but are not limited to, achieving gas-separation efficiencies, obtaining high concentrations of one or more desired separated product gas, converting and/or separating one or more gas species, chemically converting one or more of the separated gas species, and combinations thereof.

Generally, the vortex tube 10 may be configured to convert a gas flow initially homogeneous in temperature into two separate flows of higher and lower temperatures. Such separation of the one temperature-homogenous flow, which can be gaseous or liquid, into streams of higher and lower temperature is referred to as the temperature, or energy, separation effect. FIG. 1 illustrates an exemplary vortex tube 10. The vortex tube 10 may include one or more inlet nozzles 12, a vortex chamber 14, a cold-end orifice 16, and a hot end control valve 18. The vortex tube 10 includes an outer encompassing wall 20 and a central axis Ci extending from the cold-end orifice 16 to the hot end control valve 18.

The vortex tube 10 can also be used to separate components of a non-homogenous gaseous mixture, with greater separation achieved with greater differences in the mass weight of the constituent components. The centripetal force F of an object of mass m moving at tangential speed v along a path with radius of curvature r is

F=mα=mv ² /r  (EQ. 1)

wherein α is the centripetal acceleration. Alternatively, rewriting in terms of radius,

r=MV ² /F  (EQ. 2)

In separation of gas species of different molecular weight, those of lighter weight may be accelerated to higher velocities and hence be found at greater radius within the vortex tube 10. Since the hot exit is generally along the outer wall 20 of the vortex tube 10, and the cold exit is generally along the central axis C₁, mass and/or velocity of the input gas stream may determine efficiency of separation. For example, if the input velocity of the gas is not sufficient (e.g., less <30 m/s), then temperature-energy separation effects may dominate. Since the gas velocity is higher (e.g., in a range from 60 m/s to 600 m/s) in shorter tubes than longer tubes (e.g., due to energy dissipation effects), short vortex tubes can be used for separation of gas-stream components, and longer vortex tubes can be used for temperature separation effects.

As higher inlet pressures to the vortex tube 10 correspond to higher gas velocities, higher inlet pressures may be configured to achieve significant separation efficiencies (e.g., when the mass difference between the species is not considerable, such as that between CO₂ and nitrogen, with CO₂ being 57% heavier, or CO₂ and oxygen, with CO₂ being 38% heavier). In some embodiments, a two-dimensional (2D) computational fluid dynamics (CFD) model may be configured to model the gas-separation ability of a counter-flow vortex tube. The 2D CFD model, Fluent 6.3.26, may be a steady-state axisymmetric model configured to utilize both the standard and renormalization group K-epsilon (k-ε) turbulence models combined with the compressible Navier-stokes equations. The input may be an air (80% nitrogen, 20% oxygen) and CO₂ mixture. In an exemplary embodiment, the vortex tube 10 may be configured with an inner diameter D₁ of about 8 mm and a length L₁ of about 180 mm. The cold end orifice 16 may have a diameter of about 4 mm. The vortex tube 10 may include four input nozzles 12 with each input nozzle 12 having a diameter of about 2 mm. The distance D2 between the input nozzles 12 and cold end orifice 16 may be about 1 mm. A mesh of 31,140 grid elements may be used, with grid geometry generated using GAMBIT. The temperature at the inlet nozzles 12 may be at about 300 K. Using a second order upwind scheme, the continuity and the momentum equations may be solved for the averaged input mixture properties (velocity, density, and viscosity).

With a cold exit mass fraction held constant at 0.5, FIG. 2 shows the CO₂-air separation efficiency as a function of inlet pressure for an inlet gas mixture of 20% CO₂ and 80% air. Data points were determined numerically as described, while the line is a third order polynomial curve fit. As shown in FIG. 2 , as the inlet pressure of the vortex tube 10 increases so does the gas separation efficiency, with the effect ultimately saturating. CO₂ separation efficiency is determined by CO₂ concentration leaving the hot exit less CO₂ concentration leaving cold exit, and is a function of the cold mass fraction which is, in turn, dependent upon vortex tube geometrical features, surface roughness of the inner walls, composition of the input gas, and operating temperature. By configuring the dimensions of the vortex tube 10, and using an operating pressure above 4 bar, CO₂ can be separated from a gas mixture at efficiencies greater than 10%. Further, time-varying periodic modulation of the inlet pressure, and hence inlet gas velocity, can be used to promote separation. The time-periodic modulations in pressure, alternating series of higher and then lower pressures, or gas velocity, may be configured to result in the lighter gas specie(s) shifting towards a larger radius, and hence the hot exit. For example, the vortex tube 10 may have a CO₂ containing gaseous stream the operating pressure of which may vary with time in a periodic manner to create a pressure wave thereby enhancing separation and/or subsequent collection of the CO₂ entering the vortex tube 10. In some embodiments, configurations of the dimensions of the vortex tube 10 may be configured to achieve CO₂ separation equal to or greater than 5% with either time varying or steady state velocity of the input gas.

In some embodiments, the gaseous input stream entering the vortex tube 10 has a pressure of 7 bar (103 psia) or above. In one embodiment, the gaseous input stream entering the vortex tube 10 has a pressure greater than 105 psi above atmospheric, for example, between 105 psi and 280 psi above atmospheric (prig). Higher pressures allow the vortex tube 10 to be shorter while increasing the separation based on molecular weight

In some embodiments, the vortex tube 10 is configured to separate CO₂ from a gaseous input stream wherein the input concentration of CO₂ is less than 2000 ppm. In other embodiments, the vortex tube 10 may be configured to separate CO₂ from a gaseous input stream primarily comprising of nitrogen and oxygen wherein the input concentration of CO₂ is less than 2000 ppm. In some embodiments, the vortex tube 10 may be configured to separate CO₂ from a gaseous input stream wherein CO₂ comprises 21.5% or more of the input stream.

As the concentration of CO₂ in the gas stream entering the vortex tube 10 increases, the curve of FIG. 2 shifts upward, with higher separation efficiencies achieved for higher input CO₂ concentrations. Since gas separation efficiency increases with increasing concentration of target species in the gaseous (fluid) input, a series-cascade of vortex tubes 10 can be used to rapidly remove and concentrate one or more gas species.

Referring to FIG. 3 , in some embodiments, the series-cascade of the vortex tubes 10 a-10 n can be used to remove and/or concentrate one or more gas species. In some embodiments, the series cascade of the vortex tubes 10 a-10 b may be used to remove CO₂ directly from the atmosphere, subsequently allowing its sequestration or, ideally, conversion into other chemical compounds such as methane or ethane. For example, the CO₂-rich exit of the one vortex tube 10 a may be used as the input of a subsequent vortex tube 10 b. With regards to the series of vortex tubes 10 a-10 n, at each stage the dimensions of the vortex tube 10, and operating conditions to include inlet pressure or inlet gas velocity, can be configured to optimize separation properties of specific compound concentrations (e.g., CO₂). For example, the initial vortex tube 10 a may be configured to separate CO₂ present in an input gas stream at less than 2000 ppm. Another vortex tube 10 b can be configured to separate CO₂ at higher concentrations, and so on, until the desired CO₂ concentration, up to 100%, is obtained. Further, the operational features of the vortex tubes 10 a-10 n may be configured to allow higher efficiency separation as the input concentration of the desired species increases with each stage of the series-cascade.

In some embodiments, one or more vortex tubes 10 may be fabricated via three-dimensional printing techniques.

In some embodiments, operation of one or more vortex tubes 10 may be in ambient temperatures less than 48° C. and/or a temperature at which temperature (energy) separation effects do not overwhelm species separation. In some embodiments, operation of one or more vortex tubes 10 may be in temperatures configured to promote thermolysis of one or more of the gas species input to the vortex tube 10, with separation of resultant product gas species integral to the operation of the vortex tube 10.

In some embodiments, the vortex tube 10 may be configured to separate one or more components of an input gas mixture and convert one or more of the separated species. One or more components of the vortex tube 10 or series cascade of the vortex tubes 10 a-10 n can be integrated with one or more photocatalytic, triboelectric, electrocatalytic, and/or solar thermal technologies configured to directly convert the separated CO₂ into another chemical compound. For example, in some embodiments, one or more surfaces of one or more vortex tubes 10 may be modified with one or more materials (e.g., piezoelectric material) configured to provide triboelectric promoted chemical changes. In using piezoelectric material, passage of the gas stream over the piezoelectric surface generates charge that in turn can be used to promote chemical conversion. In some embodiments, concentrated solar thermal energy (e.g., solar tower), may be configured to elevate the temperature of the vortex tube 10 near or above the dissociation temperature of the separated gas specie(s), allowing simultaneous conversion and separation within the vortex tube 10, or separation and subsequent conversion.

In some embodiments, one or more connecting pipes 30 may be positioned between vortex tubes 10 a-10 n in the series-connected cascaded vortex tubes. In some embodiments, one or more of the connecting 30 pipe(s) can be formed of optically transparent material (e.g., quartz, glass). In some embodiments, one or more connecting pipe(s) 30 may be lined with a chemical-conversion promoting photocatalyst and/or contain a chemical-conversion promoting photocatalyst. For example, in CO₂ separation, the separated CO₂ exiting the vortex tube 10 a may be directed via at least one connecting pipe 30 to the subsequent vortex tube 10 b for further separation and/or concentration. The at least one connecting pipe 30 may be formed of one or more optically transparent material and/or lined with a light-responsive photocatalyst that, in combination with water vapor, under concentrated sunlight, converts the CO₂ and H₂O into CH₄ or higher order hydrocarbons such as ethane. CH₄ being significantly lighter than either CO₂, nitrogen, or oxygen, may provide for ready separation from the gas stream. In some embodiments, the one or more vortex tubes 10 and/or connecting pipe(s) 30 may include microscale or nanoscale surface topology of one or more compositions configured to promote conversion of CO₂. In some embodiments, a connecting pipe 30′ directs the separated CO₂ exiting the vortex tube 10 n to a CO₂ conversion system 32. The CO₂ conversion system 32 can be capable of converting the separated CO₂ into another chemical compound.

Referring now to FIG. 4 , in one embodiment, an electrically conductive wire 34 can be axially placed within the vortex tube 10′ along what is commonly referred to as the cold-axis, and an electric field can be generated between the wire 34 and an electrically conducting outer vortex tube wall 20 of the vortex tube 10′. We refer to the design of FIG. 4 as an Electric Field Assisted Ranque-Hilsch (EFARH) vortex tube. The electrical conductor and outer wall are not in electrical contact and thus can sustain a difference in electrical potential, by which in turn an electric field and magnetic field are generated the geometry of which are shown in FIG. 5 . In one embodiment, an electrical potential is applied between the axially oriented conductive wire and an outer electrically conductive wall of the vortex tube. Such potential can be, for example, between about 0.01 mV and about 6,000 V. Regarding the axially directed electrical conductor, such axially directed electrical conductor can be constructed of a conductive wire. Wires of greater diameter will be more disruptive to gas flow and thus product separation, therefore, all else being equal, thinner wires of smaller diameter are preferred. In some embodiments, the diameter of the axially directed electrical conductor can be within a range from 1 micron to 10 mm. Preferably, the axially directed electrical conductor is an uninsulated wire (i.e., is devoid of an electrically insulating covering), and is sufficiently rigid so as to avoid deformation when the vortex is being generated around the axially directed electrical conductor.

During EFARH vortex tube operation an electrical potential can be generated between the conductive axial wire and outer wall due to triboelectric charging effects inherent in the difference in molecule/particle velocities, and/or weights, at the two surfaces. With respect to the use of relatively long EFARH vortex tubes that promote temperature separation, it is known that molecular charge configuration is temperature dependent, thus a charge of one polarity can be induced upon the surface of the outer wall, the hot exit, with that of the other polarity induced at the surface of the inner axial wire, the cold exit.

With respect to the use of relatively short EFARH vortex tubes that promote separation of molecular species by weight, molecular triboelectric charging characteristics vary with specie, and stretching of a given molecule, or specie, which is a function of rotational velocity (centrifugal force) within the vortex tube. To clarify, stretching of a molecular bond, a common example is the OH bond, changes its polarity, and how a molecule is stretched depends upon rotational velocity about the axis of the vortex tube and whether or not the molecules undergo collisions as the molecules travel. It is recognized that the triboelectric charging behavior is dependent upon the specific input gas/vapor species, material surface properties, gas velocities, and operating temperature. Lightning, as a relevant example, is generated within storm clouds when water vapor droplets become super cooled transitioning between a liquid/solid state, at which point droplet (or water particle) charging becomes nonlinear, with sudden orders of magnitude increases in the rates of charging having been measured.

An electric field can be readily generated within an EFARH vortex tube, between the electrically conductive axial wire and the vortex tube outer wall, by connection to the high/low terminals of a voltage generator, a standard piece of electrical equipment commonly available.

In one embodiment, either the axially oriented conductive wire or the enclosing exterior wall of the EFARH vortex tube is electrically grounded, while if both elements are grounded no electric field can be generated between them.

An electric field of larger or smaller magnitude, and time-varying polarity, can be obtained by the combination of an applied potential with that arising from triboelectric charging. The applied field can be static or time varying, in this way being specifically tailored to promote certain chemical reactions. Generally, what ultimately limits the magnitude of the electrical potential between inner wire and outer wall, is the permittivity of the intervening space, and its constituents. While an electrical discharge might be suitable for promoting some chemical reactions, for example conversion of oxygen to ozone, generally speaking working with electrical sparks, due to dielectric breakdown, are to be avoided to minimize damage to working surfaces.

In one embodiment, the interior operational surfaces of an EFARH vortex tube are coated with a catalytic material, for example Rh, Cu, Fe, W, Pt, Pt/Cu, or Rh/Cu nanoparticles, or their oxide or nitride counterparts, to promote specific chemical reactions.

The EFARH vortex tube design can be used to promote simultaneous separation of polar molecules and conversion of chemical species. Further, multiple EFARH vortex tubes can be series-connected, as might be desired to sequentially increase the purity of a specific output product. In some embodiments, it may be desirable to combine the outputs of parallel-operated EFARH vortex tubes to enable the precise mixture, or combination, of specific chemical species. In some embodiments, the output of EFARH vortex tubes is passed into, or directed to, further chemical reaction chambers for additional processing, for example a subsequent Ranque-Hilsch vortex tube, or a thermal, catalytic, or photocatalytic reactor.

As discussed above, the electric field can be static or time varying, generated by applying an electric potential between the conductive wire along the cold-axis and the outer vortex tube wall. This electric field can be used to modulate chemical reactions, as well as generate a translational force capable of promoting specie separation. The applied electric field can be used separately, or in combination with the electric field generated by triboelectric means.

Renewable energy sources (e.g., wind-turbines, photovoltaics, and the like) can be used to generate electricity, which in turn can be used to collect and compress air, with the air then passed through one or more vortex tubes 10 for CO₂ separation, collection, and/or conversion in accordance with the present disclosure. In some embodiments, one or more auxiliary equipment (e.g., pumps, compressors, and the like) may be exclusively powered by energy originating from renewable sources (e.g., sunlight, wind) including, but not limited to photovoltaics, wind turbines, and the like. In some embodiments, one or more vortex tubes 10 may be used (e.g., connected in series) and between inputs and outputs of the vortex tubes 10, one or more pumps and/or compressors may be positioned to provide operational pressure. Energy used to operate the one or more pumps and/or compressors may be provided exclusively via the one or more renewable sources (e.g., sunlight, wind) by photovoltaics, wind turbines, and/or the like.

In some embodiments, the separated CO₂ can be collected, temporarily held in a storage tank, and then in batch-reactor type operation subsequently passed on to a conversion stage, (e.g. such as a high temperature thermolysis unit), with the converted product then sent on to one or more vortex tubes 10 for subsequent separation. In some embodiments, the storage tank may include one or more pressure sensing members configured to detect maximum and/or minimum set pressures in the storage tank. The storage tank may also include at least one Solenoid valve configured to adjust an amount of compound (e.g., CO₂), introduced into the storage tank according to pressure variation of the stored compound, and a control member controlling on/off of the compressor according to sensed pressure in the storage tank.

From the above description, it is clear that the present disclosure is well adapted to carry out the objects and to attain the advantages mentioned herein, as well as those inherent in the disclosure. While exemplary embodiments have been described for purposed of this disclosure, it will be understood that numerous changes may be made which will readily suggest themselves to those skilled in the art and which are accomplished within the spirit of the present disclosure.

REFERENCES CITED

-   1. G. J. Ranque, Experiences sur la detente giratoire avec     simultanes d'un echappement d'air chaud et d'un enchappement d'air     froid, J. Phys. Radium 4 (1933) 112-114. -   2. R. Hilsch, The use of the expansion of gases in a centrifugal     field as cooling process. Rev. Sci. Instruments 18 (1947) 108-113. -   3. C. U. Linderstrom-Lang, Gas separation in the Ranque-Hilsch     vortex tube. Int. J. Heat Mass Transfer 7 (1964) 1195-1206. -   4. M. R. Kulkarni, C. R. Sardesai, Enrichment of methane     concentration via separation of gases using vortex tubes. J. Energy     Eng. 128 (2002) 1-12. -   5. J. Yun, Y. Kim, S. Yu, Feasibility study of carbon dioxide     separation from gas mixture by vortex tube. Int. J. Heat and Mass     Transfer 126 (2018) 353-361. -   6. S. Mohammadi, F. Farhadi, Experimental and numerical study of the     gas-gas separation efficiency in a Ranque-Hilsch vortex tube.     Separation and Purification Technology 138 (2014) 177-185. -   7. L. A. Fekete, Vortex tube process and apparatus, U.S. Pat. No.     3,546,891 (1970). 8. H. M. Skye, G. F. Nellis, S. A. Klein,     Comparison of CFD analysis to empirical data in a commercial vortex     tube. Int. J. Refrigeration 29 (2006) 71-80. 

What is claimed is:
 1. A modified Ranque-Hilsch vortex tube comprising: a vortex tube having a cold exit, a hot exit, and a tube axis, the vortex tube made of conductive metal; a cone valve positioned in the hot exit; and an electrically conductive wire oriented along the tube axis, wherein the electrically conductive wire is electrically isolated from an exterior wall of vortex tube.
 2. The modified Ranque-Hilsch vortex tube of claim 1, wherein the electrically conductive wire comprises a metal selected from a group consisting of iron, nickel, platinum, palladium, niobium, copper, zinc, tin, chromium, cadmium, aluminum, titanium, vanadium, cobalt, zirconium, molybdenum, tungsten, gold, silver, and combinations thereof.
 3. The modified Ranque-Hilsch vortex tube of claim 1, wherein the axially oriented conductive wire is made of stainless steel.
 4. The modified Ranque-Hilsch vortex tube of claim 1, wherein the vortex tube comprises stainless steel.
 5. The modified Ranque-Hilsch vortex tube of claim 1 in which the axially oriented wire has a diameter less than 10 mm and greater than 0 mm.
 6. The modified Ranque-Hilsch vortex tube of claim 1, further comprising an internal surface at least partially coated with a triboelectric material.
 7. The modified Ranque-Hilsch vortex tube of claim 6, wherein the triboelectric material is selected from the group consisting of zinc oxide, barium titanate, and combinations thereof.
 8. The modified Ranque-Hilsch vortex tube of claim 1, further comprising an internal surface at least partially coated with a catalytic material.
 9. The modified Ranque-Hilsch vortex tube of claim 8, wherein the catalytic material comprises an element selected from the group consisting of B, Rh, Cu, W, Pd, Fe, Au, Ag, Zn, Sn, Pt, and combinations thereof.
 10. The modified Ranque-Hilsch vortex tube of claim 8, wherein the catalytic material is in combination with Pt/Cu, Pd/Cu, or Rh/Cu, either as a continuous film, non-homogenous film, or in nanoparticle form.
 11. The modified Ranque-Hilsch vortex tube of claim 1, further comprising internal surfaces at least partially coated with a metal oxide or metal nitride material.
 12. The modified Ranque-Hilsch vortex tube of claim 1, wherein neither the axially oriented electrically conductive wire nor a metallic enclosing wall of the vortex tube are grounded.
 13. The modified Ranque-Hilsch vortex tube of claim 1, wherein either the axially oriented electrically conductive wire or metallic outer wall of the vortex tube is grounded.
 14. The modified Ranque-Hilsch vortex tube of claim 1 in which a surface of the axially oriented electrically conductive wire, or a surface of an enclosing vortex tube wall, or both manifest a surface topology designed to promote triboelectric charging.
 15. The modified Ranque-Hilsch vortex tube of claim 1, further comprising an interior surface topology and composition designed to promote chemical conversion of separated product through triboelectric charging and catalytic conversion.
 16. The modified Ranque-Hilsch vortex tube of claim 1, constructed at least in part of an electrically conductive material selected from the group consisting of aluminum, brass, titanium, stainless steel, electrically conductive plastic, and combinations thereof.
 17. The modified Ranque-Hilsch vortex tube of claim 1, wherein the vortex tube comprises an inner surface coated with a catalyst that responds to one gas product but not to another gas product.
 18. A method for processing a gaseous mixture, the method comprising: feeding the gaseous mixture to the modified Ranque-Hilsch vortex tube of claim 1, wherein the inlet operating pressure is greater than about 4 bar and less than about 40 bar.
 19. A method for processing a gaseous mixture, the method comprising: feeding the gaseous mixture to the modified Ranque-Hilsch vortex tube of claim 1, wherein an electrical potential is applied between the axially oriented conductive wire and an outer electrically conductive wall of the vortex tube, and wherein the potential is constant or varies with time.
 20. A method for processing a gaseous mixture, the method comprising: feeding the gaseous mixture to the modified Ranque-Hilsch vortex tube of claim 1, wherein an electrical potential is applied between the axially oriented conductive wire and an outer electrically conductive wall of the vortex tube, and wherein the potential is greater than 0.01 mV and less than about 6,000 V.
 21. A method for processing a gaseous mixture, the method comprising: feeding the gaseous mixture to the modified Ranque-Hilsch vortex tube (EFARH) of claim 1, wherein a potential is applied between the axially oriented conductive wire and an outer electrically conductive wall of the vortex tube, and the resulting externally applied potential is superimposed upon the electric field generated by EFARH vortex tube operation.
 22. A method for processing a gaseous mixture, the method comprising: feeding the gaseous mixture to the modified Ranque-Hilsch vortex tube of claim 1, wherein the gaseous mixture contains water vapor, and wherein the operating temperature is such that super-cooled water droplets are formed.
 23. A method for processing a gaseous mixture, the method comprising: feeding the gaseous mixture to the modified Ranque-Hilsch vortex tube of claim 1, wherein the gaseous mixture contains CO₂ and water vapor.
 24. A method for processing a gaseous mixture, the method comprising: feeding a CO₂-containing gaseous mixture to the modified Ranque-Hilsch vortex tube of claim 1, wherein an electrical potential is applied between the axially oriented conductive wire and an outer electrically conductive wall of the vortex tube, and wherein the dimensions of the vortex tube, the velocity of the input CO₂-containing gaseous mixture, and the applied electrical potential are chosen to achieve an optimal degree of CO₂ separation efficiency.
 25. A method for processing a gaseous mixture, the method comprising: feeding a CO₂-containing gaseous mixture to the modified Ranque-Hilsch vortex tube of claim 1, wherein an electrical potential is applied between the axially oriented conductive wire and an outer electrically conductive wall of the vortex tube, and wherein the CO₂-containing gaseous mixture is input with a CO₂ concentration of less than 4000 ppm.
 26. A method for processing a gaseous mixture, the method comprising: feeding the gaseous mixture to the modified Ranque-Hilsch vortex tube of claim 1, wherein gas is input at a pressure that varies as a function of time.
 27. A method for processing a gaseous mixture, the method comprising: feeding the gaseous mixture to the modified Ranque-Hilsch vortex tube of claim 1, wherein an operating temperature is selected such that one or more chemical species in the gaseous mixture form super-cooled droplets.
 28. A method for processing a gaseous mixture, the method comprising: feeding the gaseous mixture to the modified Ranque-Hilsch vortex tube of claim 1, wherein an operating temperature is selected sufficient to promote thermolysis of one or more gas species input to the vortex tube; and separating resultant product gas species integral to operation of the vortex tube.
 29. A method for processing a gaseous mixture, the method comprising: feeding the gaseous mixture comprising CO₂ to a series of two or more modified Ranque-Hilsch vortex tubes as in claim 1, wherein CO₂ is separated and collected from the gaseous mixture to form a concentrated output, and wherein at least a portion of the concentrated output is fed to a device that converts CO₂ into another chemical compound. 